Application Of Surface-enhanced Raman Spectroscopy To Determination Of 6-benzyladenine, Hg²⁺ And Rhodamine B

Surface-Enhanced Raman spectroscopy(SERS) gets rapid development in recent years, due to its abilities of chemical structure recognition, less sample consumption, and nondestructive or noncontact measurements of samples contained in glass or plastic containers. Nowadays, SERS is widely used in various fields of research, including biomolecular detection and quantification, chemical reaction mechanism, single molecule detection, food and environmental analysis. In this thesis, citrate-coated silver nanoparticles(Ag NPs) were synthesized and used as SERS substrates for the determination of 6-benzyladenine(6-BA) in bean sprouts, Hg2+ in drinking mineral water, and Rhodamine B in chili powder by SERS.(1)A novel method for the determination of 6-BA in bean sprouts and Hg2+ in drinking mineral water by SERS were established, using citrate-coated silver nanoparticles as SERS substrate. The effects of type of aggregation agent, type and level of p H buffer solution, amount of silver nanoparticles solution, mixing time, concentration of 6-BA, and reaction time on the SERS signals were investigated. Under the optimized experimental conditions, good linear responses were obtained for 6-BA and Hg2+ in the concentration ranges of 10-200 μg L-1 and 5-200 μg L-1, respectively. The method was applied to the determination of determination of 6-BA in bean sprouts and Hg2+ in drinking mineral water samples, with recoveries in the range of 85.5-113.0% and 98.2-111.5%, relative standard deviation lower than 6% and 4%, respectively.(2)A rapid method to determine of Rhodamine B in chili powder by SERS was developed, using citrate-coated silver nanoparticles as SERS substrate. The effects of several experimental parameters on the intensity of SERS signals, such as volume of silver nanoparticles colloid, volume of hydrochloric acid solution, volume of Rhodamine B solution and mixing time were investigated. Combined with a portable Raman spectrometer, samples could be analyzed easily and rapidly. The LOD of Rhodamine B obtained by the present method was 0.08 μg L-1. The method was applied to determine Rhodamine B in real chili powder samples, with recoveries in the range of 81.4-97.2% and relative standard deviation lower than 5%.